LETREC

LETREC (“Parallel, recursive”) begins all the scopes of the local bindings at the beginning of the list in which they are established established. This permits local recursive procedures to be created.

> (letrec ((addup

(lambda (x)

(if (= x 0) 0

(+ x (addup (- x 1))) ) ) ))

(print (addup 4)) )

10

> (addup 4)

reference to undefined identifier: addup

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